Commercial and residential buildings or structures are commonly equipped with systems for regulating the temperature of the air within the building for purposes of e.g., comfort, protection of temperature sensitive contents, etc. Sometimes referred to as heating, ventilating, and air conditioning or HVAC systems, such typically include one or more components for changing the temperature of the air (i.e. air treatment components as used herein) along with one or more components for causing movement of the air within the building (i.e. blowers as used herein). For example, a refrigerant based heat pump may be provided for heating or cooling the air. Alternatively, or in addition thereto, electrically resistant heat strips and/or gas burners may be provided for heating the air. One or more blowers or fans may be provided for causing the heated or cooled air to circulate within the building in an effort to treat all or some controlled portion of air in the building. Ducting and vents may be used to help distribute and return air from different rooms or zones within the building.
Typically, an HVAC system is controlled by a single thermostat having a fixed location in the building being treated. In conventional systems, the thermostat typically measures the air temperature at this same fixed location. This temperature measurement is compared with a set point temperature and the HVAC system is activated or deactivated depending upon whether the set point temperature has been reached or, more commonly, depending upon whether the temperature difference between the set point temperature and the air temperature measured by the thermostat is sufficient to trigger activation or deactivation.
Although simplistic, such conventional system has certain deficiencies. For example, the air temperature as measured by the thermostat may not be representative of the air temperature at other locations in the building. Such other locations may be separate rooms and/or other locations (sometimes referred to as “zones” or “temperature zones”) remote enough from the thermostat to be at a different air temperature than the air near the thermostat. For residential buildings, the thermostat is frequently placed along a hall located well within the interior of the building. The air in rooms that include one or more exterior walls of the building may be heated or cooled more rapidly than air in the hallway. As a result, the temperature gradient or temperature difference between the air temperature at the thermostat and the air in such rooms may be substantial. Yet, even though the air temperature in such rooms may be much different than the set point temperature desired, the thermostat may not activate the HVAC system because the air temperature at the thermostat may be at, or close to, the set point temperature.
Conversely, the thermostat could be in an area that that is subject to substantial temperature fluctuations that trigger the operation of the HVAC system even though the air temperatures throughout a substantial portion of the building are close to the desired setpoint. As a result, the HVAC system will continue to operate in order to drive the air temperature near the thermostat towards the setpoint temperature—causing other portions of the building to be colder or hotter than desired.
Temperature gradients within the building may not be limited to those between the air temperature measured at the thermostat and the air at a remote room. There may also be temperature gradients between various rooms in the building. For example, a room having an exterior wall located on one end of a building may have an air temperature quite different from that of another room located at a different end of the building. This can be caused, e.g., by differences in solar heating of the building based on its orientation relative to the path of the sun over the course of the day. These differences can also be affected by the time of the year such as summer versus winter seasons.
Such problems can lead to e.g., user discomfort in different rooms or zones of the building, inefficient operation of the HVAC system, and other problems. Also, a user may attempt to manipulate the set point temperature of the HVAC system, which can inefficiently increase energy usage and may only exacerbate the problem.
By way of example, one potential solution is to use multiple thermostats placed throughout the building. However, this approach can add substantial additional cost to the HVAC system. Furthermore, simply activating the HVAC system because one of the thermostats experience an air temperature that is not at the setpoint may not effectively reduce temperature gradients throughout the building.
Accordingly, a system for reducing the temperature gradients between various rooms or temperature zones within a building would be useful. More particularly, a system that provides for a more uniform temperature within the building would be beneficial. Such a system that can operate one or more blowers of an HVAC system to reduce such temperature gradients would be particularly beneficial. Such a system that can also be used with a variety of different building types and/or configurations would also be very useful.